Tell me, what is love?

What is love... I think I don't know... Probably, at different time, at different stages of the relationship is something different. It is impossible to give one specific definition. Either it will be something fuzzy, unclear. "Love lives three years" - the title of the novel Beigbeder. He may be right?! Three years is a magical time, romance, moonlit walks, trips to the bar, noisy, crazy things... And then?! After three years of marriage?! Habit?! Caring about each other is Love?! Good attitude to each other is Love?! Respect... Maybe it's part of love?! And there is nothing more... Or is that enough?! If someone reads this post - tell me what love is.